Glaucoma affects millions of Americans, but it is unclear how often impairment results from glaucoma. Understanding when impairment occurs is critical so that treatment can be tailored to achieve the ultimate goal of glaucoma treatment: death without visual disability. In this grant, we propose to define when, and in whom, glaucoma produces visual impairment. This will be studied through functional testing - in which task performance is directly observed and measured. Emphasis will be placed on defining conditions which decrease glaucoma-related impairment, and developing rehabilitative strategies to address such impairment. Training in the grant period will focus on learning how to test for functional impairment, perform complicated data analyses, and design and conduct clinical rehabilitative trials. Dr. Ramulu's long-term goals will be to use functional testing protocols to test the efficacy of rehabilitative strategies in the visually impaired, and to test for treatment efficacy in areas where standard measures of vision are poor surrogates for visual ability.